Technical Abstract:
The NAEW was established in 1935 to develop and evaluate the effectiveness of conservation measures in reducing runoff and erosion in the hilly, humid, conditions of the northeastern United States. Small (0.5 to 1 ha), single-practice, gaged watersheds comprised of sandstone- and shale-derived residual soils are used to evaluate the interaction of management, climate, ,and soils. In a 28-year, 9-watershed study, 92% of the erosion occurred during the corn years of a 4-year corn/wheat/meadow/meadow rotation. These watersheds were plowed prior to planting corn and cultivation was used for weed control. By tilling and planting on the contour and increasing fertility levels, soil loss was reduced more than 3-fold, but still averaged 4.7 Mg/ha during corn years. Thus, annual production of row crops on a sustainable basis was precluded. A 6-year, 6-watershed study indicated that by using reduced tillage (no-till, chisel, or paraplow) and herbicides, corn and soybean can be grown in rotation with an average soil loss of 0.5 Mg/ha, well below the stipulated soil loss tolerance. Under these conditions, however, concentrations of surface-applied herbicides and nitrate in runoff frequently exceeded drinking water standards in the first few runoff events after application and may be a concern. A reduced-input management practice with light disking and cultivation for weed control and manure and a legume to supply some of the nitrogen was implemented to determine if a balance between losses of soil and purchased chemical inputs could be obtained. In a 6-year comparison, soil losses were similar to those under conservation tillage, but the risk of yield loss increased due to inability to cultivate in a timely manner due to weather conditions.